DE102007060550A1 - System and process for low emission combustion - Google Patents

Abstract

A turbine system (10) includes a compressor (12) for compressing air (20) to produce a pressurized air stream (22), an air separation unit (18) for receiving and disassembling at least a portion of the compressed air stream into oxygen and a low oxygen stream (28), a combustor (14) for receiving and combusting at least a portion of the low oxygen stream (28) of a portion of the compressed air stream and a fuel for producing high temperature exhaust gas (32) and a turbine (16) for receiving and expanding the high temperature gas (36) Generating electricity and a low-temperature NO <SUB> x </ SUB> exhaust gas (36).

Description

background

The The invention relates generally to gasification and combustion technologies and in particular, methods and apparatus for low emission combustion.

Integrated Combustion Combination Cycle (IGCC) systems are a promising technology for power generation because they allow the possibility of generating electricity from abundant fuels such as fuels. As coal, biomass, petroleum coke, municipal waste and other fuel material with reduced emissions allow. An IGCC system typically includes an air separation unit (ASU), a gasification system, and a gas turbine combination cycle system. High pressure pressurized oxygen is generated in the ASU and sent to a gasifier. In the gasifier, fuel material reacts with the oxygen in the presence of steam to produce carbon monoxide (CO) and hydrogen (H ₂ ) rich synthesis gas. The synthesis gas containing hydrogen is burned in the combustion chamber of the gas turbine combination cycle system. Current synthesis gas combustors are diffusion combustors and steam is commonly used as a diluent to reduce thermal nitric oxide (NO _x ) formation. The use of steam as a diluent in syngas combustion entails a limitation in the maximum turbine inlet temperature that can be achieved, thus limiting maximum efficiency.

Some from the challenges currently being encountered in commercialization IGCC energy generation systems involve high capital costs compared to other power generation technologies, such as B. from Pulverized coal plants. To the overall efficiency of the IGCC system are currently undergoing different integration processes for different Subsystems examined. Some of these include the feeder of the for the Synthesis gas purification and combustion dilution required steam from the heat recovery steam generator (HRSG) of the gas turbine system, as well as the compression of the ASU required air using the compressor of the gas turbine.

Accordingly, there remains a need for further integration of the various subsystems of the IGCC system to increase overall efficiency and a developmental need for combustion technologies that allow higher turbine inlet temperatures without correspondingly increasing thermal NO _x production.

SUMMARY

A turbine system includes a compressor for compressing air to produce a stream of compressed air, an air separation unit for receiving and disassembling at least a portion of the compressed air stream into oxygen and a low oxygen stream, a combustor for receiving and combusting at least a portion of the low oxygen stream, a portion of the compressed air stream, and a fuel to produce high temperature exhaust gas, and a turbine for receiving and expanding the high-temperature exhaust gas lektrizität for generating e and a low _NOx exhaust gas with a reduced temperature.

DRAWINGS

These and other features, aspects and advantages of the present invention become better understood, if the following detailed description with reference to the attached drawings is read, in which same reference numerals the same parts throughout denote the drawings, wherein:

1 a schematic representation of an embodiment of the present invention is.

2 is a schematic representation of another embodiment of the present invention.

3 is a schematic representation of another embodiment of the present invention.

4 is a schematic representation of another embodiment of the present invention.

5 is a schematic representation of another embodiment of the present invention.

6 is a schematic representation of another embodiment of the present invention.

7 is a schematic representation of another embodiment of the present invention.

8th a schematic representation of another embodiment of the present invention is.

9 is a schematic representation of another embodiment of the present invention.

10 Figure 4 is a graph of NO _x data for varying values of oxygen content at the combustor inlet.

11 Figure 5 is a graph of NO _x data for varying values of oxygen content at the combustor inlet and at different combustor flame temperatures.

DETAILED DESCRIPTION

A compressor 12 , a combustion chamber 14 , a turbine 16 and an air separation unit (ASU) 18 having turbine system 12 is in 1 shown. As used herein, the term ASU means any system or subsystem that can receive air and output an oxygen stream and a low oxygen stream, and optionally a nitrogen stream. As used herein, the term oxygen flow means a stream that is greater than 80 volume percent oxygen, while the low oxygen content stream is less than about 20 volume percent oxygen.

air 20 gets into the compressor 12 compressed to a compressed air flow 22 to create. A second airflow 24 will be in the ASU 18 introduced to an oxygen (O ₂ ) stream 26 and an oxygen-poor stream 28 to create. At least part of the low-oxygen stream 28 and at least part of the compressed air flow 22 be the combustion chamber 14 for combustion with a fuel for generating a high-pressure high-temperature exhaust gas 32 fed. The high-temperature exhaust gas 32 becomes the turbine 16 for expansion and generation of electricity via a generator 34 and a low NO _x exhaust gas 36 supplied at a low temperature. As used herein, the term lean NO _x exhaust gas means an exhaust gas having less than 30 parts per million (ppm) NO _x , and typically less than 20 ppm and often less than about 10 ppm. In fact, in some embodiments, the NO _x level may be less than 5 ppm and less. The low-oxygen stream 28 Dilutes the entire oxygen content in the combustion chamber 14 , thereby reducing peak combustion temperature and NO _x production. air 20 without the dilution from the oxygen-poor stream 28 typically has an oxygen content of about 21%. By adding all or part of the low-oxygen stream 28 into the combustion chamber, the oxygen content of the combined combustion air is less than 21% and typically between about 10% to about 20% and often between 15% to about 18%. In addition, the NO _x production is also reduced due to the reduced oxygen partial pressure in the combustion flame.

In a further embodiment of the invention 50 becomes the oxygen-poor stream 28 a compressor 51 fed and together with air 20 compressed to a mixed compressed air flow 52 as shown in 2 to create. The mixed compressed air flow 52 becomes a combustion chamber 14 for combustion with fuel 20 for generating high pressure high temperature exhaust gas 32 fed. The high-temperature exhaust gas 32 becomes a turbine 16 for expansion and generation of electricity via a generator 34 and _x-poor of NO gas 36 supplied at a reduced temperature. In one embodiment of the invention, the compressor 51 a first stage compressor section 54 and a second stage compressor section 56 on. In one embodiment, the oxygen-poor stream 28 in the second stage compressor section 56 for mixing with a compressed air stream 58 from the first stage compressor section 54 directed. In yet another embodiment, an optional intercooler takes 60 the low-oxygen stream 28 and the compressed air flow 58 and mixes them to a mixed compressed air flow 62 to produce the second stage compressor section 56 for compression is supplied to a mixed compressed air flow 52 to create. This embodiment is particularly attractive since various commercial gas turbine systems, such as. For example, the GE LMS 100 currently uses a multi-stage compressor and intercooler, making retrofit applications both desirable and practical.

In a further embodiment of the invention, the compressed air flow 22 into two streams of a first part 102 and a second part 104 as shown in 3 divided up. The first part 102 of compressed air flow 22 becomes the ASU 18 fed to an oxygen stream 26 and an oxygen-poor stream 28 to create. The second part 104 becomes an optional mixer 106 fed where the second part 104 with the oxygen-poor electricity 28 is mixed to a mixed stream 108 to create. The mixed stream 108 then becomes the combustion chamber 14 for combustion with fuel 30 fed. (Alternatively, the second part 104 and the oxygen-poor electricity 28 into the combustion chamber 14 passed). In this embodiment, the system advantageously uses only one compression cycle around both the combustion chamber 14 to guided air as well as the ASU 18 compressed air to thereby save capital investment, operating and maintenance costs and to limit the total area requirements of the system.

In a further embodiment 200 The invention is the oxygen flow 26 a gasification device 200 fed, where he with a carbonaceous material 204 reacts to a synthesis gas 206 as shown in 4 to create. A part 208 of the oxygen stream can be split and used elsewhere, for example, the part 208 recorded, stored and transported. The synthesis gas 206 becomes a synthesis gas processing system 210 for the conversion of the synthesis gas 206 in a purified fuel 212 fed. The cleaned fuel 212 gets into a combustion chamber 114 for combustion with the mixed stream 108 introduced. This embodiment provides the advantage of using a solution with low NO _x for existing gasification systems. Most gasification systems include an ASU as a standard component of the system, so system integration would be easy.

In a further embodiment 300 The invention relates to the compressor 12 a first-stage compressor 302 and a second stage compressor 304 as shown in 5 on. The air 305 becomes the first-stage compressor 302 for generating a compressed air flow 306 supplied to the ASU 18 is supplied. The second stage compressor 304 takes the air 20 and generates a compressed air flow 22 , the mixer 106 for mixing the compressed air flow 22 with the oxygen-poor electricity 28 is supplied.

In a further embodiment 400 The invention relates to the oxygen-poor stream 28 in the second stage compressor 304 introduced and together with air 20 compressed to a mixed compressed air flow 402 as shown in 6 to create. The mixed compressed air flow 402 becomes a combustion chamber 14 for combustion with the purified combustible fuel 212 supplied to high-pressure high-temperature exhaust gas 32 to create. The high-temperature exhaust gas 32 becomes the turbine 16 for expansion and generation of electricity via a generator 34 and _x-poor of NO gas 36 supplied at a reduced temperature. In yet another embodiment of the invention takes an optional intercooler 310 the low-oxygen stream 28 and at least part of the compressed air flow 306 on, and mix it to a mixed stream 312 to produce the second stage compressor section 304 for compression is supplied to a mixed compressed air flow 402 to create.

In a further embodiment 500 The invention will be related to 1 is further modified to include an exhaust gas recirculation (EGR) circuit as discussed in U.S.P. 7 is shown. That by the turbine 16 generated low _NOx exhaust gas 36 is a heat recovery steam generator (HRSG) 502 for the production of steam 504 and of exhaust 506 supplied at a reduced temperature. The steam 504 typically is supplied to a steam turbine post-scavenging circuit (not shown) for generating additional electricity. The exhaust 506 with reduced temperature is a current splitter device 508 for the distribution of the exhaust gas 506 with reduced temperature in at least a first part 510 and a second part 512 fed. In one embodiment, the first part becomes 510 a carbon dioxide withdrawal system 514 supplied for the removal and isolation of carbon dioxide contained in the stream. In a first embodiment, the first part is 510 between about 50% to about 80% of the exhaust gas 506 with reduced temperature.

The second part 512 the exhaust gas 506 at a reduced temperature, typically via a pump 516 , a water removal system 518 , such as As a condenser, for removing the entire excess water and generating an oxygen-poor, low-water stream 520 fed. In one embodiment, the second part lies 512 between about 20% to about 50% of the exhaust gas 506 with reduced temperature. The oxygen-poor, low-water stream 520 becomes a compressor 12 for compression together with air 20 fed to a low-oxygen compressed air stream 522 to create. The NO _x production in the combustion chamber 14 is significantly reduced compared to conventional systems because the combustion chamber 14 several streams with a reduced oxygen content, a low-oxygen compressed air stream 522 and an oxygen-poor stream 28 receives. No _x production is reduced due to the reduced oxygen partial pressure in the combustion flame and the lower temperature of the flame compared to the combustion of atmospheric air. In addition, the elimination of carbon dioxide in this system is much facilitated since the first part 510 the exhaust gas 506 with reduced temperature has a lower flow rate and a higher carbon dioxide content, which makes the removal and isolation of carbon dioxide much more efficient with a smaller total area requirement. In one embodiment 600 becomes a low-water stream 520 in a heat exchanger 602 together with a low-oxygen stream 28 introduced to the heat exchange between them, as the temperature of the low-water stream 520 before entering the compressor 12 is reduced and the temperature of the oxygen-poor stream 28 before entering the combustion chamber 14 is increased, as is in 8th is shown.

In a further embodiment 700 the invention is with reference to 5 is further modified to include an exhaust gas recirculation (EGR) circuit as shown in FIG 9 contains. The oxygen-poor, low-water stream 520 gets the compressor 12 for compression together with air 20 for generating an oxygen-poor compressed air flow 522 fed.

10 FIG. 12 is a graphical representation of a NO _x reduction (corrected for 15 volume percent oxygen) demonstrated in certain experiments plotted against the oxygen level at the inlet of the combustor held at a fixed flame temperature of about 1593 ° C (2900 ° F). As shown in the data, a significant reduction in NO _x occurs when the oxygen content in the combustion air changes from the standard 21% by volume to 14% by volume. As demonstrated in these experiments, an NO _x reduction of about 80 percent is measured at an oxygen content level of 14% t compared to the baseline level of 21% oxygen content.

11 is another graph that demonstrated in certain experiments (15 volume percent oxygen corrected) NO _x values plotted against the oxygen level at the combustor inlet for three different flame temperatures of about 1426 ° C (2600 ° F), about 1528 ° C ( 2800 ° F) and about 1649 ° C (3000 ° F). As shown in the data, a significant reduction in NO _x levels occurs as soon as the oxygen content in the combustion air changes from the standard 21% by volume to about 16% by volume and less. As shown for all three flame temperatures, the NO _x values at 16 volume percent oxygen are less than 10 ppm and in one case less than 5 ppm, which represents a significant reduction in NO _x values from the baseline.

Even though only a few specific features of the invention are illustrated herein and are described, many modifications and changes for the expert be evident in the field. It should therefore be understood that the attached claims all such modifications and changes as far as they are in the actual Invention ideas of the invention are intended to cover.

10

turbine system

12

compressor

14

combustion chamber

16

turbine

18

Air separation unit (ASU)

20

air

22

Compressed air flow

24

second airflow

26

oxygen stream

28

Low oxygen electricity

30

fuel

32

High-temperature exhaust gas

34

generator

36

Low-temperature low-NOx NO _x exhaust

50

Further embodiment the invention

51

compressor

52

Mixing compressed air flow

54

First-stage compressor section

56

Second stage compressor section

58

Compressed air flow

60

intercooler

62

Mixing compressed air flow

100

Further embodiment the invention

102

first section

104

second section

106

mixer

108

mixed stream

200

Further embodiment the invention

202

gasifier

204

Carbonaceous material

206

synthesis gas

208

section

210

Synthesis gas processing system

212

purified fuel

300

Further embodiment the invention

302

First-stage compressor

304

Second-stage compressor

306

Compressed air flow

400

Further embodiment the invention

304

Second-stage compressor

402

mixed pressure flow

500

Further embodiment the invention

502

(HRSG)

504

steam

506

exhaust with reduced temperature

508

Current split means

510

first section

512

second section

514

Carbon dioxide-removal system

516

pump

518

Water disposal system

520

Poor water electricity

522

Low oxygen Compressed air flow

600

A embodiment

602

heat exchangers

700

Further embodiment the invention

Claims (13)

Turbine system ( 10 ) comprising: a compressor ( 12 ) for compressing a first air stream ( 20 ) for generating a compressed air stream ( 22 ); an air separation unit ( 18 ) for receiving and disassembling a second air stream ( 24 ) in oxygen ( 26 ) and an oxygen-poor stream ( 28 ); a combustion chamber ( 14 ) for receiving and burning at least part of the oxygen-poor stream ( 28 ), part of the compressed air flow ( 22 ) and a fuel ( 30 ) to high-temperature exhaust gas ( 32 ) to create; and a turbine ( 16 ) for receiving and expanding the high-temperature exhaust gas ( 32 () To electricity and low _NOx emission 36 ) with reduced temperature. Turbine system ( 10 ) according to claim 1, wherein the oxygen-poor stream ( 28 ) has less than about 20 volume percent oxygen. Turbine system ( 10 ) according to claim 1, wherein the NO _x low-emission exhaust gas stream ( 36 ) has a NO _x level of less than about 30 ppm. Turbine system ( 10 ) According to claim 1, wherein the low _NOx exhaust gas ( 36 ) an HRSG ( 502 ) for the production of steam and an exhaust gas ( 506 ) is supplied at a reduced temperature. Turbine system ( 10 ) according to claim 4, wherein the steam is supplied to a Nachschaltkreislauf for the generation of additional electricity. Turbine system ( 10 ) according to claim 5, wherein the exhaust gas ( 506 ) is divided at a reduced temperature into a first part corresponding to a carbon dioxide removal system ( 514 ) and into a second part of the compressor ( 12 ) for compression together with the first air stream ( 20 ) is supplied. Turbine system ( 10 ), comprising: an air separation unit ( 18 ) for decomposing air into oxygen ( 26 ) and an oxygen-poor stream ( 28 ); a compressor ( 12 ) for compressing air ( 20 ) and at least part of the oxygen-poor stream ( 28 ) to a mixed compressed air flow ( 52 ) to create; a combustion chamber ( 14 ) for receiving and burning at least part of the mixed compressed air flow (US Pat. 52 ) and a fuel ( 30 ) to a high temperature exhaust gas ( 32 ) to create; and a turbine ( 16 ) for receiving and expanding the high-temperature exhaust gas ( 32 () To electricity and low _NOx emission 36 ) with reduced temperature. Gasification system comprising: an air separation unit ( 18 ) for decomposing air into oxygen ( 26 ) and an oxygen-poor stream ( 28 ); a gasification device ( 202 ) for reacting the oxygen ( 26 ) and a carbonaceous material ( 204 ) to a synthesis gas ( 206 ) to create; a synthesis gas processing system ( 210 ) for converting the synthesis gas ( 210 ) into a purified fuel ( 212 ); and a gas turbine system ( 10 ), comprising: a compressor ( 12 ) for compressing air ( 20 ) for generating a compressed air stream ( 22 ); a combustion chamber ( 14 ) for receiving and burning at least part of the oxygen-poor stream ( 28 ) and at least part of the compressed air flow ( 22 ) and at least part of the purified combustible fuel ( 212 ) to a high temperature exhaust gas ( 32 ) to create; and a turbine ( 16 ) for receiving and expanding the high-temperature gas ( 32 () To electricity and low _NOx emission 36 ) with reduced temperature. Gasification system according to claim 8, wherein the compressor comprises at least one first stage compressor section ( 54 ) and a second stage compressor section ( 56 ) having. Gasification system according to claim 9, further comprising an intercooler ( 60 ), wherein the oxygen-poor stream ( 28 ) into the intercooler for mixing with a stream of compressed air from the first stage compressor section ( 54 ) to produce a mixed stream which is fed to the second stage compressor section ( 56 ) is supplied. A method for reducing emissions, comprising the steps of: generating an oxygen-poor stream ( 28 ); Generating a compressed air flow ( 58 ); Burning at least a portion of the low oxygen stream, a portion of the compressed air stream, and a fuel to produce a high temperature exhaust gas ( 32 ) to create; Expanding the high-temperature gas to generate electricity and a low _NOx emission. The method of reducing emissions of claim 11, further comprising the steps of: using the low NO _x exhaust gas to generate steam and exhaust gas ( 36 ) with reduced temperature. A method of reducing emissions according to claim 12, further comprising the steps of: supplying a first portion of the exhaust gas ( 36 ) at a reduced temperature to a carbon dioxide removal system ( 514 ); and compressing and mixing a second portion of the exhaust gas ( 36 ) at a reduced temperature with the air stream to produce an oxygen-poor compressed air stream.